MusicSchool

This site has musical games and quizzes that provide excellent, fun, learning resources for grade 6 and 7 students.  It also provides many links to other sites with similar facilities.

DSOforKids

The Dallas Symphony Orchestra site has a wealth of listening resources for young people, including samples of all orchestral instruments.  It also provides time-lines and composer details as well as games and other interactive fun stuff.  All is very brightly-coloured and  appealing to students.

ClassicsForKids

This has lesson plans and teaching resources based on the US National Standards for the Arts and state Academic Content Standards for Music.  It has a great supply of short radio programmes on different eras and styles of music.